U.S. patent number 4,720,374 [Application Number 06/757,576] was granted by the patent office on 1988-01-19 for container having a sonication compartment.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Narayanaswamy Ramachandran.
United States Patent |
4,720,374 |
Ramachandran |
January 19, 1988 |
Container having a sonication compartment
Abstract
A container for the dissolution of a tablet of material is
characterized by a plurality of projections mounted within the
container. The projections cooperate to define a tablet-receiving
recess adapted to confine a tablet inwardly therewithin in a
relatively high energy zone during sonication of the tablet. Gaps
between the projections define recirculating liquid channels
whereby hydrating liquid passing through the tablet-receiving
recess may be recirculated to other regions of the compartment.
Inventors: |
Ramachandran; Narayanaswamy
(Newark, DE) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
25048363 |
Appl.
No.: |
06/757,576 |
Filed: |
July 22, 1985 |
Current U.S.
Class: |
422/310; 206/538;
422/128; 422/261; 422/568; 422/940 |
Current CPC
Class: |
B01L
3/5085 (20130101); B01F 2215/0037 (20130101); G01N
2035/0436 (20130101); B01L 2300/0858 (20130101); B01L
2400/086 (20130101); B01L 2300/0609 (20130101) |
Current International
Class: |
B01L
3/00 (20060101); G01N 001/10 () |
Field of
Search: |
;422/58,61,65,102,261,266,310,128 ;206/.5,524.7,538,539,569
;220/213,229,359 ;356/244,246 ;435/805 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Richman; Barry S.
Assistant Examiner: Johnson; William R.
Claims
What is claimed is:
1. A container having a hydration compartment adapted to receive
therein a hydrating liquid and a material to be dissolved or
dispersed thereinto, the compartment having sidewalls and endwalls
and a floor from which an array of finger-like members project
vertically upwardly into the compartment, the fingers being spaced
from the sidewalls and endwalls with the tips of predetermined ones
of the finger-like members being above the tips of others of the
members within the compartment, the members being arranged with
respect to each other to define a material receiving recess and
being relatively spaced apart to define recirculating gaps
therebetween such that, in use, the material to be dissolved by the
application of ultrasonic energy from a source introduced into the
compartment is confined within a relatively high energy zone
defined by the recess and hydrating fluid is recirculated through
and out of the relatively high energy zone through the gaps between
the finger-like members.
2. The container of claim 1 further comprising planar members
having side surfaces extending substantially perpendicularly of the
floor, the planar members being oriented substantially on diagonals
of the compartment.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Subject matter disclosed herein is disclosed or claimed in the
following copending applications filed contemporaneously
herewith:
Method and Apparatus for Ultrasonic Interface Detection, filed July
22, 1985 and accorded Ser. No. 757,572; now abandoned;
Self-Cleaning Ultrasonic Horn, filed July 22, 1985 and accorded
Ser. No. 757,574; and
Resealable Lid Structure For A Container, filed July 22, 1985, and
accorded Ser. No. 757,575.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a container configured to
facilitate the dissolution or dispersion of tableted or partially
emulsified material using ultrasonic energy.
2. Description of the Prior Art
Techniques are known in the art whereby ultrasonic energy is
utilized to dissolve tableted material. Exemplary of such prior
knowledge is U.S. Pat. No. 3,582,285 (Hamilton) which discloses a
package for tableted chemicals. Ultrasonic energy is applied from
the exterior of the package and coupled into a reaction compartment
such that a tablet of material disposed within the compartment is
dissolved. The patent's disclosure recognizes that the application
of ultrasonic energy results in the creation of relatively high
sonic energy zones within the compartment. However, experience has
shown that a tableted material tends to migrate and the fragments
produced by sonic dissolution tend to disperse within the
compartment from the high energy zone to zones of relatively less
energy. As a result relatively long periods of exposure to
ultrasonic energy may be required to completely dissolve the
material of the tablet.
Such prolonged sonication may result in excess heating of the body
of liquid in which the tablet is disposed. This excessive heating
may be especially deleterious when the tableted material is being
dissolved within a body of liquid (e.g., a sample and/or reagent)
that is used for the analysis of biological liquids. Accordingly,
it would be advantageous to provide a container arrangement whereby
tableted or partially emulsified material may be dissolved or
dispersed expeditiously (i.e., in less than one minute) by the
application of ultrasonic energy from a point in the interior of
the container. Further, it is believed advantageous to provide a
container which exhibits a structure which confines the tableted
material to a relatively high energy zone thereby preventing the
migration of the material, tablet or portions of the tablet from
this zone, thus decreasing the dissolution time.
When storing a liquid reagent and/or specimen care must be
exercised to minimize evaporation. Simultaneously, however,
whatever structure is used to inhibit evaporation must be
compatible with the requirements of access to the liquid during
use. Accordingly it is believed advantageous to provide a lid
structure which is resealable to permit extended storage without
evaporation and, simultaneously to accommodate mixing or sampling
probes. Lid structures which realize these goals are available in
the art. Exemplary of such devices is that disclosed in U.S. Pat.
No. 3,994,594 (Sandrock et al.). However, such lid structures are
believed incompatible for use in an environment in which the mixing
and/or sampling probe is other than a sharp implement. Moreover, in
multi-compartmented containers it is believed desirable to provide
a lid structure which minimizes vapor transmission from compartment
to compartment, thus minimizing contamination of the contents of
one compartment by the contents of another compartment.
The source of sonic energy used for dissolving tableted material is
a device known as an ultrasonic horn. The horn is a relatively
elongated member which vibrates at an ultrasonic frequency as a
result of a conversion of an electrical excitation signal into a
mechanical vibration. Ultrasonic horns may be provided with a bore
through which a liquid may be flowed through the horn and out of
the tip. This structure allows injection of one liquid into
another, as in emulsion formulation, misting or fogging. Such
ultrasonic horns are produced by, among others, Heat Systems -
Ultrasonics Inc., Farmingdale, N.Y. Other horn structures are known
which operate as atomizers by pumping a liquid from a reservoir by
the pumping action generated as a result of an asymmetric sound
field forming bubbles in the bore. Exemplary of this type of device
is that shown in the Article by Lierke, "Ultrasonic Atomizer
Incorporating A Self-Acting Liquid Supply", 5 Ultrasonics, 214
(1967).
However, when using a flow-through horn in a biological testing
environment care must be taken to prevent "carry-over", i.e.,
contamination of a subsequent liquid with particulate matter
deposited within the horn by a preceding liquid. It would therefore
be advantageous to provide an ultrasonic horn assembly having a
self-cleaning capability such that the carry-over of particulate
matter is minimized or eliminated.
SUMMARY OF THE INVENTION
The present invention relates to a container having a hydration
compartment defined therein. The container may receive a hydrating
liquid and one or more tablets of solid material to be dissolved or
dispersed therein. The container has an array of
sonication-improving projections mounted therein which cooperate to
define a tablet-receiving recess. The projections are spaced from
each other to provide recirculating channels which communicate with
both the tablet-receiving recess and the remainder of the volume of
the container such that, in use, the projections act to confine a
tableted material within a relatively high ultrasonic energy zone
and simultaneously permit a flow of hydrating liquid from the high
energy zone through the channels thereby to rapidly effect the
dissolution of the tableted material.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be more fully understood from the following
detailed description thereof taken in connection with the
accompanying drawings which form a part of this application and in
which:
FIG. 1 is a plan view of multi-container strip useful for carrying
a liquid for biological testing in which each container has a
compartment with a tablet-receiving recess defined by a plurality
of projections formed therewithin;
FIG. 2 is a side elevational view taken along section lines 2--2 of
FIG. 1;
FIG. 3A through 3D are each plan views of an individual container
illustrating alternate embodiments of the tablet-receiving recess
defined by projections in accordance with the present
invention;
FIG. 4 is a plan view of a resealable lid structure usable with a
multi-compartment container of FIG. 1;
FIG. 5 is a sectional view of the lid structure taken along lines
5--5 of FIG. 4; and
FIG. 6 is a side sectional view of an ultrasonic horn in accordance
with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Throughout the following detailed description similar reference
numbers refer to similar elements in all figures of the
drawings.
Referring to FIG. 1 shown is a plurality of hydration containers
10A through 10F conveniently arranged in an end-to-end relationship
to form a container strip generally indicated by the reference
character 12. As will be developed more fully herein each of the
containers 10A through 10F is provided with an array of the
preferred form of sonication-improving projections generally
indicated by reference character 30 provided in accordance with the
present invention.
The container strip 12 may be fabricated in any convenient manner.
In the embodiment shown in FIG. 1 the container strip 12 includes a
rigid peripheral band 14 formed of a suitable material, such as an
inert plastic. The band 14 is either joined to or formed integrally
with each of the containers 10 such that, in the preferred case,
the container strip 12 generally tapers in a substantially
elongated wedge-like manner from a first edge 16L toward a second
edge 16R. This wedge-shaped plan profile for the container strip 12
facilitates the mounting of a plurality of such strips in a
circumferentially adjacent, generally radially extending
relationship across a rotatable reagent carrying plate such as that
disclosed in the analysis instrument disclosed and claimed in
copending application titled Analysis Instrument Having Heat-Formed
Analysis Cuvettes, Ser. No. 642,814, filed Aug. 21, 1984 and
assigned to the assignee of the present invention. It should,
however, be appreciated that the individual containers 10 may take
any predetermined configuration and the containers 10 may be used
alone or arranged together in any convenient number and in any
convenient manner and remain within the contemplation of this
invention.
Each of the containers 10, whether arranged singularly or in a
container strip 12, in the embodiment shown, is formed of a
suitable inert plastic material and includes a compartment defined
by generally opposed pairs of generally parallel and integrally
formed sidewalls 18A, 18B and end walls 20A, 20B. The upper
surfaces of the sidewalls 18A and 18B and endwalls 20A and 20B
(together with the upper surface of the band 14 in the vicinity
thereof) register to define a substantially planar sealing surface
22 peripherally surrounding the open upper end of the container 10.
The compartment of the container 10 is closed by a downwardly
sloping inverted pyramidal floor 24 (FIG. 2). In the embodiment
shown in FIG. 1 the sidewalls 18A, 18B of each container 10 are
joined to the peripheral band 14. Further, the endwall 20A of the
container 10A and the endwall 20B of the container 10F are likewise
connected to the band 14. The band 14 extends slightly below the
lower ends of the containers 10 and thus define a support strut 26
whereby the container strip 12 may be set on a suitable work
surface. It the container 10 were used singly any convenient
arrangement may be used to support the container on a work surface.
As seen in FIG. 1 the containers 10A, 10B, 10C and 10D are arranged
in a substantially square configuration while the containers 10E
and 10F are configured in a more rectangular configuration.
However, it is to be understood that individual containers may be
defined to be other than rectangular or square in plan and be
provided with other than a downwardly sloping floor 24 and yet
remain within the contemplation of the present invention.
Adjacent endwalls 20A, 20B of adjacent containers 10 (e.g., the
containers 10B, 10C and 10D, FIG. 2) are spaced from each other by
a predetermined gap 28 to enhance the thermal and vapor isolation
of each of the containers 10. In accordance with the preferred
embodiment of the invention the container strip 12 is formed by
injection molding from a polyallomer material. Of course, other
manufacturing techniques and materials of construction may be
utilized and remain within the contemplation of the present
invention.
As noted earlier, in accordance with the present invention each of
the containers 10 carries an array of mutually spaced sonication
improving projections 30. The individual projections 30 are spaced
from each other to define channels 32 therebetween. With reference
to FIGS. 1 and 2 the preferred embodiment of the projections 30 is
shown. In this embodiment the projections 30 take the form of a set
of substantially finger-like members 36, 36' extending vertically
upwardly in axially parallel relationship from the floor 24 of each
container 10. Selected ones 36 of the finger-like members project
upwardly from the floor 24 for a distance greater than the others
36' of the members of the set. Such a relationship thereby defines
a tablet-receiving recess 38 disposed generally centrally within
the container 10. The spaces between the finger-like members 36,
36' define channels 32 which, as will be explained herein, permit
hydrating liquid flow into and through the recess 38. It should be
appreciated that the sonication improving projections 30 may be
disposed in any convenient orientation or at any convenient
location within the container 10. For example, if the finger-like
members 36, 36' are used to define the projections 30, such members
may be inclined with respect to the vertical axis of the container
10 and may be mounted to the sidewalls 18A, 18B and/or the endwalls
20A, 20B in addition to or in place of their mounting on the floor
24. As also seen from FIGS. 1 and 2 generally planar members 40
extend diagonally outwardly from the corners of the container 10 to
assist in guiding of the circulating hydrating liquid. As seen the
side surfaces of the planar members 40 lie substantially
perpendicularly to the floor 24.
Other embodiments of the sonication improving projections 30 are
shown in FIGS. 3A through 3D. These figures depict plan views of
individual containers 10 and illustrate the form and arrangement
with vertical side surfaces of alternate embodiments of the
sonication improving projections. In FIG. 3A the projections 30 are
in the form of plate-like members 42 generally similar to the
members 40 shown in FIGS. 1 and 2. Some of the plates 42 extend
inwardly from the corners of the container 10 while others 42'
extend inwardly from the container from the sidewalls 18 and
endwalls 20 thereof. The plates 42, 42' are thus respectively
oriented substantially along diagonals and transverses of the
container 10. The inner ends of the plates 42, 42' preferably, but
not necessarily, extend substantially vertically of the container
10 from the floor 24 of the container. The lower edges of the
plates 42, 42' may integrate with the floor 24, if desired. The
vertically oriented inner ends of the plates 42, 42' cooperate to
define on the interior of the container the centrally located
tablet-receiving recess 38. The spaces between the plates 42, 42'
define the channels 32 through which hydrated liquid may flow in a
manner to be described.
In FIG. 3B the projections 30 are in the form of inwardly directed
pyramid structures 46, 46'. The pyramidal structures 46, 46' are
each defined by faces 48, which are joined along an apex 50 that
substantially align in the respective cases of the structures 46
and 46' with the diagonals and transverses of the container 10. The
structures 46, 46' are thus mounted in positions analogous to the
plates 42, 42' and are thus substantially diagonally and
transversely disposed within the container 10. The spaces between
the structures 46, 46' define the channels 32 for the purpose to be
described.
In FIG. 3C the floor 24 of the container 10 is provided with a
central circular region 54 which is intersected by diagonal grooves
56 thereby to respectively define the tablet-receiving recess 38
and the channels 32. In this and in FIG. 3D the floor 24 is
substantially flat. The projections 30 are thus defined as those
portions of the material of the container 10 between the grooves
56. Similarly, in FIG. 3D the central region 54 again defines the
recess 38. In this instance the region 54 is interrupted by a
plurality of generally parallel grooves 58 which serve to define
the channels 32. End grooves 60 are also provided. The projections
32 are defined as those portions of the material between the
grooves 58, 60.
In the use of this invention a tableted material to be dissolved or
dispersed in introduced into a hydrating liquid introduced within
the container. Sonifying energy is provided from an ultrasonic
transducer such as the device (discussed in connection with FIG. 6)
lowered into the container 10 through the open end thereof.
Actuation of the ultrasonic transducer introduces ultrasonic energy
and directs the same substantially axially of the container to
encompass the tablet-receiving recess 38. The ultrasonic energy may
be applied continuously or in bursts, with a relatively constant or
varying frequency. The tablet (or plurality of tablets) of material
to be dissolved or dispersed into the liquid in the container
migrates toward and is confined within tablet receiving recess 38.
It is found that the migration of the material to the recess 38
occurs whatever the initial disposition of the material within the
container 10. The structural relationship between the projections
30 serves to define a recess 38 which defines a relatively high
ultrasonic energy region within the container in which the material
to be dissolved is received and confined. Any entrapped air beneath
the material to be dissolved and hydrating liquid flow is permitted
from other regions on the interior volume of the container through
the high energy sonication region and then outwardly through the
channels 32 between the projections 30. It is believed that if the
embodiment of the projections 30 shown in FIGS. 1 and 2, i.e., the
finger-like members, is used reflection of ultrasonic energy from
the walls and floor of the container into the recess 38. As a
result of the confinement of the material to the high energy zone
relatively high speed dissolution of the material due to the
application of ultrasonic energy may be effected. Times of
dissolution of the material of less than one minute are possible.
Concomitantly heating effects which may deleteriously affect the
hydrating liquid and/or the chemical release by dissolution are
thereby avoided.
In view of the foregoing those skilled in the art may readily
appreciate that the provision of any suitable projections disposed
either on the floor and/or from the walls of the container which
serve to define both a tablet-receiving recess and recirculating
gaps to permit the circulation of hydrating liquid through the high
energy zone act in use to enhance the application of ultrasonic
energy to efficiently and expeditiously dissolve the tablet
material. Any such structural combination which forms the
relatively high energy tablet-receiving recess and defines a
relatively high ultrasonic energy zone coupled with and
communicating recirculating channels lies within the contemplation
of the present invention.
An ultrasonic transducer or probe 64 in accordance with the present
invention is shown in FIG. 6. The body or horn portion 66 of the
transducer 64 is an elongated axial member extending from an
enlarged head portion 68 to a beveled tip 70. The tip 70 defines an
angle 72 measured with respect to a reference line perpendicular to
the axis of the bore within the range from 0.degree. to 45.degree.,
more particularly from 30.degree. to 45.degree., and precisely
30.degree.. An axially projecting threaded boss 74 extends upwardly
from the head 68. A pair of piezoelectric crystals 76A, 76B with
associated electrodes 78A, 78B are received about the boss 74.
Leads 80A, 80B extend from the electrodes 78A, 78B,
respectively.
In the embodiment shown in FIG. 6 the crystals 76 are held in place
against the head 68 by a backpiece 82. A nut 84 threads onto the
boss 74 and clamps the assembly together. A tubing connector 85 is
threadedly received onto the upper portion of the threads of the
nut 84. A tube 86 mounted within the connector 84 may thus be
quickly and easily interconnected with the ultrasonic transducer
64.
A bore 88 extends centrally and axially through transducer 66 where
it communicates with the end of the tube 86. The internal diameters
of the tube 86 and the upper portion 88A of the bore 88 are
substantially equal. As seen in FIG. 6 the relatively larger
diameter portion 88A extends over substantially all of the length
of the transducer 66. Disposed within a predetermined distance 90
of the end of the horn 66 is an inwardly tapering beveled shoulder
92. The presence of the shoulder 92 narrows the bore 88 to a lesser
diameter portion 88B. In accordance with the invention the shoulder
92 is located within the predetermined close distance 90 from the
antinode (or the tip of the beveled end 66) of the vibrating horn
62.
In operation the tube 86 is connected to suitable aspirating and
hydrating sources whereby hydrating liquid may be dispensed from
and aspirated into the transducer 64. To minimize the possibility
of carry-over of matter in the bore 88 the bore 88 is cleaned by
the microstreaming and cavitating action produced by the abutment
of the shoulder 92 against a continuous column 93 of liquid
extending a predetermined distance 94 into the enlarged portion 88A
of the bore.
An ultrasonic horn assembly 64 as shown in FIG. 6 is adapted to
precisely dispense and aspirate liquid into and from a container 10
and to provide the sonic energy necessary to dissolve a tablet or
partially emulsified material. The horn assembly 64 can also be
used to mix together at least two liquid materials. Due to the
provision of the shoulder 92 the cleaning action generated within
the continuous column 94 of liquid is generated which prevents
accumulation of matter on the walls of the bore and thus minimizes
carryover. It is also believed that the cleaning action extends
into liquid within the tube 86, thus minimizing carryover at the
interface between the horn and the tube.
The horn assembly 64 may also form a part of an apparatus for
detecting the presence of a solid interface (e.g., a lid) or a
liquid interface (e.g., the surface of a liquid reagent or a liquid
sample.
The leads 80A, 80B are applied to a self resonant power supply
network 95 such as that disclosed in U.S. Pat. No. 4,445,064, which
patent is incorporated by reference herein. The network 95 includes
a motional bridge circuit 96 for generating feedback signals
proportional to the vibration of the ultrasonic horn assembly 64
which is modified by means of an active filter 97 in the feedback
circuit which is coupled to a starting circuit 98 that raises the Q
of the active filter when a signal is not present in the feedback
loop to change the active filter from a mode suppressant to a
self-oscillating state.
As seen in FIG. 6, the horn assembly 64 is operated in a motional
bridge circuit 96 which, in turn, is coupled to the output of
constant gain power amplifier 99 via a transformer 100. The
motional bridge circuit 96, not only serves to apply excitation
power to horn 64, but more importantly, it produces a sinusoidal
feedback control voltage on line 101 that (1) corresponds directly
with transducer tip frequency, amplitude and phase and (2) remains
independent of nonreactive load changes on the transducer. Line 101
connects the motional bridge circuit 96 to the input of the all
pass phase shifter circuit 102. Connected to the output of phase
shifter 102 is the active filter circuit 97 and the starting
circuit 98 to make filter 97 self oscillating. Active filter 97 is
connected to the input of power amplifier 99 whose output is
connected to transformer 100 through inductance 103 to drive
motional bridge circuit 96.
Feedback control voltage of line 101 is the input to phase shifter
circuit 102 which is used to tune the phasing of the input
sinusoidal signal in such a predetermined amount and direction that
the transducer vibrations are constrained to remain in the parallel
resonance condition. It is important to note that only the phasing
of the feedback signal, and not amplitude, is adjusted so as to not
disturb loop gain and the mode suppression function of succeeding
active filter circuit 97. Phase shifter circuit 102 is configured
as a first-order all pass network with variable phase shift. Its
output is a replica (except for phase) of the input AC feedback
signal from motional bridge circuit 96.
Active filter 97 is a dual-purpose second-order Q-controlled band
pass filter. The primary purpose of filter 97 is to prevent the
power supply from driving the transducer system "out of band" into
vibrational modes that have not been selected for use. Used in this
way, it is called a mode suppressant filter. The secondary purpose
of filter 97 does not appear unless the feedback signal on line 101
is lost completely, such as at startup. In this event, starting
circuit 98 which monitors the output signal from phase-shifter
circuit 102, causes the Q of active filter circuit 97 to increase
to the point where filter circuit 97 brakes into oscillation.
(Circiut Q is defined as the ratio of resonant frequency (W.sub.o)
to -3 dB bandwidth (BW) or
The frequency of oscillation is made to be coincident with the
preselected natural parallel resonant frequency of the transducer
system. The oscillator mode afforded by active filter 97 remains as
long as needed to re-establish the feedback control signal on line
101 from motional bridge circuit 96.
A voltage (on the order of seventy volts, RMS) is applied to the
horn 64 which is sufficient to just drive the unloaded horn 64 to
vibrate at its resonant frequency. The horn operates in the
frequency range from 20 to 100 kHz., more particularly 40 to 60
kHz, and specifically at 50 kHz. When the tip 70 of the horn 64
encounters the solid or liquid interface the horn becomes loaded
and the horn no longer resonates. The signal in the line 101 is
thus lost. As described above and in the incorporated patent the
loss of the feedback signal causes the starting circuit 98 to
produce a signal on the line 104 to a device 105, e.g., a digital
computer. Thus is generated an indication that the horn 64 has
encountered an interface.
Each of the containers 10 in the multi-container strip 12 shown in
FIG. 1 may be closed by a lid structure L in accordance with the
present invention. The lid structure includes a first, lower,
support sheet 106 having an array of spaced receptacles 107
therein. Each receptacle 107 occupies a perimetric configuration
corresponding to the shape of the open end of the container 10 with
which it is associated.
A second, upper, cover sheet 108 overlies the lower sheet 106. The
sheet 108 is joined to the sheet 106 along those interfacing
portions thereof to thus define a substantially enclosed volume 110
within each receptacle 107. The sheets 106 and 108 are joined by
any suitable expedient and define a peripheral flange region 112
entirely surrounding the enclosed volume 110. Disposed within each
of the volumes 110 is a thermoplastic elastomer pad 112 such as
that sold by West Company of Phoenixville, Pa., under formulation
number 8553-3-5-1. The pad 114 is received within each enclosed
volume 110 and is sized such that a gap 116 is defined between the
walls of the receptacle and the undersurface of the upper sheet
108.
The lid structure L in the above-described assembled relationship
is arranged to overlie each container 10 in the strip 12. To
facilitate this end the undersurface of the peripheral flange
region 112 defined by the jointure of the sheets 106, 108 is heat
sealed or otherwise attached to the sealing surface 22 of the
compartments 12. In this manner the containers are each closed by
an impermeable seal which serves to form an evaporation barrier for
the contents of the compartment and to isolate the containers
against vapor cross contamination.
Since in the embodiment shown in FIGS. 4 and 5 lower sheet 106 is
to be heat sealed to the surface 22 surrounding each container, the
material of the sheet 106 abutting the container 10 must be heat
sealable thereto. Otherwise any suitable substantially rigid, inert
material may be used as the sheet 106. The sheet 108 is, in the
preferred embodiment formed of a laminate of (i) an outer polyester
film, such as that sold by E. I. du Pont de Nemours and Company
under the trademark MYLAR, (ii) a polyvinylidene chloride coating
such as that sold by Dow Chemicals Co. under the trademark SARAN,
and (iii) an outer barrier sheet of polyethylene. The polyethylene
sheet interfaces against the lower sheet and is joined thereto. Of
course, any other suitable materials may be used for the sheets 106
and 108. The top sheet 108 forms a vapor barrier to enhance the
shelf life of a container covered by the lid L.
The pad 116 may also be implemented using any stretchable,
resealable material, such as silicone rubber or natural rubber. In
the preferred embodiment the lid is arranged such that the pad 114
projects downwardly into the container. However, the reverse is
also possible, i.e., where pad 114 is disposed above the container.
If only a single container is being covered the lid may be
implemented using a single sheet with a pad secured thereto. Either
surface of the sheet may be attached to the container whereby the
pad projects into or lies above the container.
The pad 114 may be provided with a slit 120 which defines an entry
and exit path whereby an ultrasonic horn, e.g. the horn 64, may be
introduced into the container 10. The elastomeric material of the
pad 114 is selected so that the pad self-heals as the horn is
withdrawn, thereby maintaining a substantially integral evaporation
barrier over the container. The pad 114 self-heals even for
relative large diameter probes (i.e., on the order of 0.125
inches). Thus the lid structure L is useful in conjunction with
relatively blunt probes. Moreover, the material of the pad 114
performs a wiping action on the exterior of the horn as the horn is
inserted or withdrawn. This wiping action prevents cross
contamination. It has been found that the provision of the gap
between the pad and the receptacle facilitates the entry of the
probe or horn into the container.
Those skilled in the art having the benefit of the teachings of the
present invention as hereinabove set forth may effect numerous
modifications thereto. These modifications are, however, to be
construed as lying within the scope of the present invention as
defined by the appended claims.
* * * * *